Workpiece consecutive selection and alignment machine



June 1, 1965 A. H. LONG ETAL 3,186,332

WORKPIECE CONSECUTIVE SELECTION AND ALIGNMENT MACHINE Filed April 17, 1963 4 he ts-S ee l Tut/n A rranutv June 1965 A. H. LONG ETAL 3,186,332.

WORKPIECE CONSECUTIVE SELECTION AND ALIGNMENT MACHINE Filed April 17,- 1963 4 Sheets-Sheet 3 519.4 36. I rfijj' 9 se 1 3/ I INVENTO A: THUR H. (.auG'

fLExANMRSHAJHA rv w FIE/2 ArraluEY A. H. LONG ETAL June 1, 1965 WORKPIECE CONSECUTIVE SELECTION AND ALIGNMENT MACHINE Filed. April 17, 1963 4 Sheets-Sheet 4 INVENTO Ann/a2 H. Loud AuxAHQERSHAsHA-N THEIR A TT'ORNE'Y United States Patent 3,186,332 W URKPIEE CONSECUTEVE SELECTION AND ALIGNMENT MACHINE Arthur H. Long, Coluinbiana, and Alexander Shashaty,

Youngstown, Ohio, assignors to Wm. K. Stamets Company, Pittsburgh, Pin, a corporation of Pennsylvania Filed Apr. 17, 1963, Ser. No. 273,752 9 Claims. (Cl. 100- -7) This invention relates generally to a machine for the consecutive selection of a series of different sizes of cylindrical workpieces for bundling the same and more particularly to cam means for selecting and delivering any one of a series of cylindrical workpieces in turn and thereafter align, accumulate, and bundle the same.

The principal object of this invention is the provision of a machine provided with a cam for accepting consecutive stock pieces which are thereafter measured and accumulated to complete a group or series and are then bundled, tied, and delivered from the machine. One of the important features of this invention is to provide a cam which will accept consecutive stock pieces of circular cross section with-in a considerable range of sizes such as a pipe having the dimension of from 2% inches to 4 /2 inches in outside diameter and any size therebetween. The cam surfaces will receive and select the consecutive stock pieces and deliver them to a rotary member that passes them longitudinally to a stop to accurately align the same and allow them to continue on the skids to an accumulator which when filled with a predetermined number of aligned stock members will discharge the same into a bundling machine where they are bound within a tight bundle and discharged the same to a place of storage or transfer.

Another object is the provision of a specific cam for selecting consecutive stock pieces within a range of sizes each series of sizes being selected one at a time regardless of the speed or other manner in which the stock approaches the selector cam. The stock may be rolling fast or even bounce along the skids and strike the'selector cam but this will not interfere with its proper selection. V en the mill is changed as to size it is not necessary to change this cam selector which is a considerable job for every size of pipe or cylindrical workpiece. Again this cam may receive the work when piled one on the other and the selector cam takes the first one leaving the other workpieces on the skids.

Another object is the provision of a single selector cam having a contour that is shaped to take groups of different sizes of pipe or cylindrical members or workpieces, an outside diameter in a range such as 2% inches to 4 /2 inches. Pipe or cylindrical members of different diameter within this range can follow one another to the selector cam and the cam will select one at a time and eject the same, regardless of the diameter of the workpiece.

Another object is the provision of a set of aligning rollers the perimetral surface of each of which has a helix the bottom of which is flush with the skid surface to receive consecutivesections of pipe and convey them in one direction of a stop. The rotary axis of these rollers lies in the same vertical. plane as that of the skid.

Another object is the provision of a non-symmetrical timin cam which is keyed on the drive shaft of the aligning rollers. This cam cooperates with a follower roller which in turn, determines the movement of the selector cam so that spaced consecutive pipe sections will be supplied to aligning feed rollers. The aligning rollers and their drive shafts control the selector cams through this cooperative combination. The result of this arrangement is that for every revolution of the aligning rollers there is an ejectment by the selector cams. Therefore, the selector cams permit only one cylindrical member or workpiece at a time to come in contact with the aligning rollers for alignment.

Other objects and advantages appear hereinafter in the following description and claims.

The accompanying drawings show for the purpose of exemplification, without limiting this invention or the claims thereto, certain practical embodiments illustrating the principles of this invention wherein;

FIG. 1 is a plan view of the machine comprising this invention.

FIG. 2 is a cross sectional view taken on the line 22 in FIG. 1.

F126. 3 is an enlarged sectional view showing the nonsymmetrical timing cam and its follower FIG. 4 is an enlarged sectional view showing the selector cam and its operation.

FIG. 5 is a view in end elevation of the stop arrester.

FIG. 6 is a view showing the selector cam and the construction of its contour and shape.

Referring to FIGS. 1 and 2 of the drawings the skid members 1 are supported directly on the longitudinal beam members 2 and 3 which are in turn supported by a series of standards 4 and 5. The standards 5 supporting the beams 3 carry the series of housings 6 which contain the bearings that support the shaft 7. The housing 6 also contains beveled gears to drive the outboard rotary aligning rollers 16. Each of the bearings 8 support the selector cam shaft 10. The selector cam shaft 10 carries the selector cam members 11. Each of the cam members 11 are placed in close proximity to a skid member 1. In FIG. 1 the motor 12 operates the multiple belt drive 13 which in turn rotates the gear reducer 14, which drives the'shaft 7 through the couplings 15 and the outboard rotary aligning rollers 16. Since the rotary aligning rollers 16 are operated simultaneously from the same drive they operate in synchronism.

The selector cams 11 are oscillated from the receiving to the ejecting position through the use of a non-symmetrical rotary timing cam 17. As can be seen in PEG. 3 this rotary timing cam 17 is .of a particular shape and contour, its main proportions being offset from the center of the drive shaft 7. This cam 1'7 will rotate at the same speed as the shaft 7 and the aligning rollers. The cam 17 rotates clockwise in FIG. 3 and the follower roller 18 is pressure biased to be in constant contact therewith. The follower roller 18 is secured to a cam follower arm 20 which in turn is keyed to the rotatably supported jack pivot shaft 21. A bell crank 22 is secured to the jack pivot shaft 21 as shown in FIG. 4- which also shows the selector cam 11 in its normal position.

The bell crank 22 consists of two arms, the loading arm 23 and the actuating arm 24. The actuating arm 24 is pivotally connected to a keeper bar 25. The opposite end of the keeper bar 25 is pivotally connected to the arm 26 which in turn is keyed to the cam shaft 10 by means of the key members 9. The variable linkage 27 sets the initial position of the selector cam 11.

As shown in FIG. 4 each of the cam members 11 are secured to the cam shaft 16 through the support ring members 30 to which thecams are bolted by bolts 23. The ring members 36 are locked to the cam shaft It by keying. The lower part ofthe cam may be bifurcated as illustrated at 19 to enable it to be readily changed to suit the rangeof cylindrical members to be passed by the selector cams l1.

j The bolts 31 secure the cam plate 32 to the skid members 1. The purpose of these cam plates is to reduce excessive wear caused by rolling cylindrical members as they travel into the cam abutment-'33. Also the cam plate 32 helps to promote better selection by the cam 11 in selecting a cylindrical member and ejecting the same.

In FIG. 6 a construction is shown for a cam whose contour will receive cylindrical workpieces within any range of diameters depending upon the size of the cam 11 and its abutment 33. It is again pointed out that these cams are bifurcated in order that they are readily changeable to meet the different diametrical specification of cylindrical workpieces.

The abutment 33 is made up of the arc segments of the circles and a straight line. The construction lines 76 and 77 represent the point of reference from which all measurements are referred. Starting at the point 78 of the cam surface 36, the surface contour of the abutment 3 3 is formed by the are 81) of a circle of radius Stir. The arc 84 leaves the surface of the abutment at a projection and point of intersection, indicated as 81, which point is on the are 82 of a circle whose radius is 82r. The arc 32 takes up where the larger are 80 left off and continues on to form the contour of the abutment 33 until a point indicated as 83. At this point a straight line 84 tangential to that point on the are 82 continues on to form the surface of the abutment 33. At a point indicated as 85, the line 84 is tangential with the are 86 of a circle whose radius is 861 and this are segment terminates at a point 87, thereby completing the contour of the abutment 33.

In practice it has been found that this particular shape or contour of the cam 11 is excellent for the needed careful selection by the cam 11 of the cylindrical workpieces of different diameters. Under the general construction as shown in FIG. 6, the radius 82;- represents the smallest radius of a workpiece for selection by the cam 11 and the radius 8dr represents the largest radius of a workpiece that can be selected by this cam. Thus the cam 11 may be employed to select a series of pipe sizes within a range including the radii of the workpieces 82w and 8614/ which may be within the capacity of the bundling machine to which this selector device is part. This novel arrangement permits these selecting cams to operate on the full range of pipe size that can be handled by such a machine without changing any of the apparatus regardless of the size as long as it is within this range.

The loading arm 23 is pivotally connected to the piston 34 of the air cylinder 35. This air cylinder is set at a predetermined pressure and functions as a pressure loading for follower roller 18 and insures a constant pressure between follower roller and the surface of the cam 17.

Each cam member 11 is of the same shape and size. The contour of the abutment 33 is made such that it will be able to take a cylindrical member or pipe of a different size within a specified range and it makes no difference whether each consecutive pipe as it approaches the abutment 33 is of a different size or not. Ordinarily only one size of pipe is selected and bundled at a time. The selector cam 11 will only take one cylindrical member or pipe at a time as long as the size of the pipe is within a specified range such as 2% inches to 4 /2 inches outside diameter. For a different range of sizes of pipe or workpieces, a different size of cam is required. The cam plate 32 cooperates with the selector cam 11 in order that the cam 11 will receive and eject one pipe or cylindrical member at a time. This cooperation is due to the fact that the cam member 11 recedes below the level of the cam plate 32 while the selector cam is in its normal extended position. This is shown in FIGS. 2 and 4.

The operation of the machine as herein disclosed is as follows. As cylindrical members such as pipe roll down the skid members 1 they will be stopped by the selector cam 11. The selector cam 11 will discharge a cylindrical member only when the irregular shaped timing cam'17 hasrotated to a position placing the follower roller 18 in the dotted line position as shown in FIG. In this figure the cam 17 has been divided up into four arcuate sections by the radii 17A, 17B, 17C, and 17D. The dwell between line 17A and 17B is an 135 arc as measured from the center of the drive shaft 7. While the roller 18 travels around this circular arc of the cam, and the selector cam 11 remains in its upright or extended position. Between the radii 17B and 17C is an arcuate section whose arcuate distance is 112. Here, the cam 17 begins to move the roller 18 from its normal position and there is continual displacement of the roller by the cam 17 until the roller reaches the radius 17C. As the roller 18 proceeds along the cam surface of this displacement arcuate section, the roller will be progressively forced from its normal position due to the fact that the distance between the center of the shaft 7 and the perimeter of the cam continually increases until the end of the dwell at the radius 17C. At this point the roller 18 has reached the dotted position as shown in FIG. 3. The roller then travels along a dwell between radius 17C and 17D on the perimeter of the cam 17, this dwell having a maximum radial distance from the center of shaft 7 than any other dwell or arcuate section on the cam perimeter. The roller 18 will travel faster on the perimeter due to increase in radial distance between the center of the shaft 7 and the roller. During this dwell of an arcuate distance of 45 the roller 18 will be maintained in the dotted position as shown in FIG. 3. At this time the selector cam 11 will be in its discharging position. The selector cam 11 remains in this position during the time the roller 18 travels along the perimeter of this dwell. The dwell period is the smallest arcuate position on the cam 17 and therefore the selector cam 11 will remain in a discharge position for a short time.

The last arcuate section of the surface of the cam 17 between the radius 17D and 17A has an arcuate distance of 68. As the roller 18 continues along the perimetral surface of the roller cam 17, the selector cam 11 will return to the normal position by the time the roller 18 has come to the end of this arcuate section. This return arcuate section has a shorter arc distance than the displacement arcuate section and also the distance between the perimeter of this arcuate section and the center of the shaft 7 continually decreases at a faster rate than the distance increases between the center of the shaft 7 and perimeter of the displacement arcuate section between radii 17 and 17C. The effect of this construction is that the roller 18 and the selector cam 11 will return quicker to their normal positions as compared to displacement of this roller and the selector cam from their normal position as theroller'18 proceeds along the displacement arcuate section.

The cam 11 in its discharge position permits the cylindrical workpiece to continue on down the skid members 1 until it engages the aligning rollers 16.

As the moving workpiece comes in contact with the aligning rollers 16,,which are rotating from left to right as viewed in FIG. 1, the workpiece will be carried from the left to the right in FIG. 1 by the rollers 16 until it comes in contact with the stop arrester 37. The purpose of these aligning rollers is to align at least one end of each pipe or cylindrical member. The pipe arrester 37, shown in FIG. 5, consists of a face plate 38 made of steel which is pivotally connected by the pin 40 to the bracket 41. The bracket 41 is bolted to a support 42 by the bolts 43. The support 42 is bolted by bolts 44 to the base member 45. The bolts 43 are very long so that the Micarta washers 46 may be placed upon each bolt. These Micarta washers contain a fabric and will compress somewhat when pressure is applied against the bracket 41. The bolt 47 has a smooth cylindrical body and cooperates with the cylindrical member 48 to form a guide. The guide bolt 47 is necessary because of the fact that since these Micarta washers .46 are made with fabric, they cannot be firmly supported in a rigid position themselves on thebracket member 41. Therefore, a strong rigid member such as the guide 48 is used in cooperation with the four bolts 43. This is necessary to provide some rigidness and support to this bracket member 41 and the face plate 38. i

The face plate 38 has connected to its pivotal end shafts 51 which are provided with the slidable counterweights 50. These shafts are clearly shown in FIG. 1. The purpose of these counterweights is to enable the face plate to be balanced by the counterweights 50 at all times. The face plate 38 being in a balanced position, therefore, cooperates with the bolts 43 and the guide bolt 47 to form an arrester or stop so that when a pipe is being positioned by the aligning roller 16 and suddenly strikes the face plate 38. The face plate 38 and the Micarta washers will absorb the shock and, therefore, reduce any rebound movement by the cylindrical member. Again, if the cylindrical member is practically aligned on coming in contact with the rollers 16, on abutting arrester 37, the cylindrical member will stop and surface of the rollers will slide thereunder until the workpiece is discharged from the same.

After the workpiece is positioned by the rollers 16 it will continue to roll down the skid members 1 where it comes in contact with the accumulator stop members 52. The purpose of these accumulator members is to hold back a predetermined amount of workpieces before they continue on to the bundling machine 53. The accumulator stop member 52 is connected to a shaft 54, which shaft is carried by a support member 55. The arm 56 is keyed to this shaft and its other end is pivotally connected to the piston 57 of the cylinder 58. The piston 57 is extended when in its normal operating position. When the cylinder is actuated and the piston 57 is withdrawn into the cylinder 58, the accumulator stop member 52 will pivot in a clockwise direction in- FIG. 2 permitting the workpieces of pipe to roll off into the circular yoke 60. The circular yoke 60 and the bundling machine are not a part of this invention and therefore is not referred to in detail. However, the circular yoke is rotated from a position as illustrated in FIG. 2 by the pistons 61 and 62 so that the open mouth 63 of the yoke is turned upwardly to release the bundled pipe 64 onto the lever arm 65. This arm in cooperation with the piston 66 and the cylinder 67 will rotatably eject the bundled pipe to the skids 68. From there the bundled pipe will slip into the sling rack 70 and stay there until mechanically taken away. The sling rack 70 is a strong coil spring. This is used because care is taken so as not to break the straps holding the bundled pipe 64 together. The sling rack 70 is secured to upstanding support beams 71 which in turn are connected to the base 72.

At times the bundling machine 53 may not be wanted to be placed in use. An attaching arm 73 may be secured to the end of the skids 1 by the hand tightening bolt 74. In FIG. 1 the securing mountings 75 for the bolts 74 are shown. With this arm 73 in operation the aligned workpieces or pipe will roll on past the bundling hopper of the bundling machine 53 and continue on to the skids 68 and roll into the sling rack 70. The machine then can function as an assembling machine by delivering pipes consecutively rather than in a complete bundle which can then be removed from the sling 70 one at a time or several at a time and be' placed in another operation. This machine then can operate as a delivering mechanism by controlling the movement and position of workpieces in an assembly operation or any other mode of operation. Although thecam 11 is provided with specific contours that are conducive to accurate handling of the cylindrical workpieces, the fundamental or basic form of this cam maybe formed by construction lines OY which pass through points 78 and 81 and OX that pass through 85 and 87. CY and OX form a right angle and OX extended passes through the axis of rotation A of the shaft 10. The convex surface 36 has the radius r1 and from the apex 87 the radiation from A is r2. The basic form of the cam lies along the lines formed by 78, 81, 0, 85 and 87 and is primarily a right angle. This basic cam has the upwardly extending line OX approximately ten degrees from the vertical construction line 77. A point or set insert at the apices 78 and 87 improves the right angle cam in that the adjacent cam surface of the ninety degree lines are then slightly receding as are the arcuate surfaces 80 and 86.

We claim:

1. A cylindrical workpiece selector including a frame, skids supported by said frame, selector cams to consecutively select cylindrical workpieces on said skids, a rotary shaft supported by said frame and transversely of said skids to support said selector cams, an arm secured to said shaft, a second rotary shaft, a bell crank lever secured to said second shaft, variable linkage between said arm and one lever of said bell crank lever, a third rotary shaft, aligning roller means driven by said third shaft and having a helical thread to receive and align each consecutive workpiece transversely to their movement on said skids, a timing cam mounted on said third shaft and having a large portion thereof extending radially of said third shaft, a cam follower secured to said second shaft to engage the perimeter of said timing cam, load means secured to the second lever of said bell crank lever to hold said cam follower in engagement with said timing cam, and means to drive said third rotary shaft to rotate said timing cam and operate said cam follower and bell crank lever to oscillate said selector cams in consecutively selecting and discharging cylindrical workpieces to said aligning roller means.

2. A device for consecutive selection of cylindrical workpieces of different sizes at difiierent times and within predetermined group sizes, which consists of a series of skids each having a downwardly sloping coplanar workpiece rolling surface, a shaft supported on a rotary axis below and transversely of said skid surfaces, a series of selector cams mounted in axial alignment on said shaft to have arcuate movement therewith with their forward portion adjacent said skids, each of said selector cams having similar cam portions to cooperate with the workpieces on said skid surfaces, drive means to provide arcuate reciprocation of said shaft to operate said selector carns, each cam at its forward portion including a first and convex arcuate abutment cam portion of uniform radius from said rotary axis that terminates in an' apex that selects the consecutive workpieces, a second and concave arcuate cam portion of uniform radius extending from said apex and becoming progressively closer to said rotary axis and terminating in a small projection, a third and concave arcuate cam portion of uniform radius starting at said small projection and extend ing progressively further from said rotary axis to a point on a tangent plane that is substantially 90 from a plane passing through said apex and said small projection, a fourth and straight cam portion extending outwardly along said tangent plane, a fifth and concave cam portion starting from said last straight cam portion and extending outwardly from said rotary axis following a uniform radius the center of which lies forward of said tangent plane and the centers of each of said other arcuate surfaces and terminating at an apex lying in said tangent plane, a sixth and convex arcuate cam portion extending from said last apex along a convex arc of uniform radius struck from said rotary axis.

3 The cam of claim 2 characterized in that the uniform radius of each arcuate cam portion is greater than the radius of the smallest of the group size of stock for selection by said selector earn.

4. The timing cam of claim 1 characterized by spaced perimetral arcuate sections of constant radius to form dwells on said timing cam between which the remaining perimetral arcuate sections of said timing cam spiral to meet the ends of said dwells to form a continuous but nonsymmetrical perimetral section, said timing cam when rotating will displace said cam follower to cause reciprocation of said selector cams and consecutively select and discharge workpieces along said skids.

5. The timing cam of claim 1 characterized in that said shafts are timed so that for every revolution of said aligning roller means there is one revolution of saidtiming cam to cause said first cam portions to consecutively select workpieces fromsaid skids and eject the same to continue to roll down said skids to said aligning roller means and to be consecutively aligned by the same.

6. The structure of claim 1 characterized by a stop arrestor adjacent one end of said frame, said aligning roller means to receive and move each consecutive workpiece longitudinally to engage said stop arrestor and then release the same to continue to roll down said skids, an accumulator to selectively retain a predetermined group of aligned workpieces on said skids, means to actuate said accumulator to release the accumulated group of workpieces, and bundling means to accept the accumulated group and bundle and discharge the same.

7. The structure of claim 1 characterized by a stop arrestor adjacent one end of said frame, said aligning roller means to receive and move each consecutive workpiece longitudinally to engage said stop arrestor and then release the same to continue to roll down said skids, an accumulator to selectively retain a predetermined group of aligned workpieces on said skids, means to actuate said accumulator to release the accumulated group of workpieces to continue on down said skids to a bin provided for removal or storage.

3. A rotary cam for the consecutive selection of cylindrical workpieces of a group of different diameters which consists of a cam body having means to mount the same for rotation, a fundamental cam surface in said body having a substantially horizontal short receiving section in one plane and a substantially vertical long discharge section in another plane with both sections disposed within a quadrant said planes of which are substantially at right angles to each other, said quadrant lies between a pair of lines that intersect with the axis of rotation of the cam body, a selection apex at the end of the short receiving section, a discharge apex at the end of the long discharge section, said fundamental cam surface continuous from one apex to the other, a peripheral convex surface extending'from said selection apex to function as a stop, a receding arcuate surface in each of said cam surface sections from each apex, the dimension of said short and long receiving sections from their apices to the 8 plane of the opposite section being greater than the diameter of the smallest workpiece of the group to be selected and greater-than the radius of the largest workpiece of the group of workpieces to be selected by the cam.

drical workpieces of a group of different diameters which consists of a cam body having means to mount the same for rotation, a fundamental cam surface in said body having a substantially horizontal short receiving section in one plane and a substantially vertical long discharge section in another plane with both sections disposed within a quadrant said planes of which are substantially at right angles to each other, said quadrant lies between a pair of lines that intersect with the axis of rotation of the cam body, a selection apex at the end of the short receiving section, a discharge apex at the end of the long discharge section, said fundamental cam surface continuous from one apex to the other, a peripheral convex surface extending from said selectionapex to function as a stop, a receding arcuate surface in' each of said cam surface sections from each apex, the dimension of said short and long receiving sections from their apices to the plane of the opposite section being greater than the diameter of the smallest workpiece of the group to be selected and greater than the radius of the largest workpiece of the group of workpieces to be selected by the cam, and a stop abutment surface in said fundamental cam surface and in the lower portion of said long discharge section and within said right angle quadrant between said planes, the face of said stop abutment engaged by the surfaces of the workpieces 1 of small diameter of the group but spanned by the surfaces of the larger workpieces of the group.

References Cited by the Examiner UNITED STATES PATENTS 369,306 8/87 Whitman l00142 825,421 7/06 Saunders 214-1 X 2,387,658 10/45 Gruber et al 10027 2,596,862 5/52 Mirfield 1007 3,039,584 6/6-2 McConnell et al. 214l X WALTER A. SCHEEL, Primary Examiner,

9. Atrotary cam for the consecutive selection of cylin- 

8. A ROTARY CAM FOR THE CONSECUTIVE SELECTION OF CYLINDRICAL WORKPIECES OF A GROUP OF DIFFERENT DIAMETERS WHICH CONSISTS OF A CAM BODY HAVING MEANS TO MOUNT THE SAME FOR ROTATION, A FUNDAMENTAL CAM SURFACE IN SAID BODY HAVING A SUBSTANTIALLY HORIZONTAL SHORT RECEIVING SECTION IN ONE PLANE AND A SUBSTANTIALLY VERTICAL LONG DISCHARGE SECTION IN ANOTHER PLANE WITH BOTH SECTIONS DISPOSED WITHIN A QUADRANT SAID PLANES OF WHICH ARE SUBSTANTIALLY AT RIGHT ANGLES TO EACH OTHER, SAID QUADRANT LIES BETWEEN A PAIR OF LINES THAT INSERSECT WITH THE AXIS OF ROTATION OF THE CAM BODY, A SELECTION APEX AT THE END OF THE SHORT RECEIVING SECTION A DISCHARGE APEX AT THE END OF THE LONG DISCHARGE SECTION, SAID FUNDAMENTAL CAM SURFACE CONTINUOUS FROM ONE APEX TO THE OTHER, A PERIPHERAL COVEX SURFACE EXTENDING FROM SAID SELECTION APEX RO FUNCTION AS A STOP, A RECEDING ARCUATE SURFACE APEX, THE DIMENSION OF SAID SURFACE SECTIONS FROM EACH APEX, THE DIMENSION OF SAID SHORT AND LONG RECEIVING SECTIONS FROM THEIR APICES TO THE PLANE TO THE OPPOSITE SECTION BEING GREATER THAN THE DIAMETER OF THE SMALLEST WORKPIECE OF THE GROUP TO BE SELECTED AND GREATER THAN THE RADIUS OF THE LARGEST WORKPIECE OF THE GROUP OF WORKPIECES TO BE SELECTED BY THE CAM. 